Circuit interrupter



March 5, 1940. .1. B. M NElLL 2,192,772

' CIRCUIT INTERRUPTER Filed Sept. 26, 1935 2 Sheets -Sheet 1 .44 53v anEl WITNESSES: INVENTOR LZZZ/Z. fa/m B. Mac/Veil].

W BY

\ ATTOR EAY March 5, 1940. I J. B. M NElLL $192,772

CIRCUIT INTERRUPTER Filed se t. 26, 1955 2 Sheets-Sheet 2 WITNESSES:INVENTOR JO/UZ B. Mac/Veil OM W ATTOR EY Patented Mar. 5, 1940 UNITEDSTATES PATENT OFFICE 2,192,112 cmom'r m'rsnauma Pennsylvania ApplicationSeptember 20, 1935, Serial 120.42.183

33 Claims. (01. 200-) My invention relatesgenerally to circuitinterrupters and more particularly to contact structures and areextinguishers for use with high capacity circuit breakers.

Heretofore the practice in the circuit breaker art has been almostuniversal in the adoption of a double break construction in which thetwo breaks of the circuit interrupter were introduced in series.However, in view of the increasing de mand for higher transmissionvoltages and for high speed interrupting operations the simple doublebreak circuit interrupter is no longer able to meet modern requirements.Generally, it may be said that for a given method of arc extinction theamount of electrode separation necessary for eiiectiveinterruption'varies nearly directly with the voltage. Although it isconceivable that a simple double break interrupter may be constructedwhich has the ability of interrupting extremely high voltages, such astructure would not meet modern requirements since the time intervalrequired to separate the movable contacts the requisite distance fromthe stationary contacts would be prohibitive.

The main object, therefore, of my invention is to provide a high voltagehigh power circuit breaker structure in which a large electrodeseparation and are extinction are accomplished in a shorter timeinterval than that required heretofore with structures of the prior art.In order to accomplish the aforenamed object, I have provided an arcinterrupting structure whereby the circuit is opened simultaneously atmore than two points so as to produce a plurality oi serially relatedarcs. The several pairs of separable contacts whereby such a pluralityof arcs are drawn are so arranged that when actuated to the open circuitposition the separation of each pair of contacts is that best suited forare extinction.

In accordance with a further object of 'my.

invention, I provide additional separable contacts in series with thosefor initially drawing .the series related arcs adapted to be openedbreaks in the controlled circuit during its operation.

A still further object of my invention is to provide a novel arrangementtor the various elements of the interrupter in order to facilitate theassembling of those elements and to render the servicing of theinterrupter easier and simpler.

The above objects and one method of accomplishing them will be made moreapparent in the following description and drawings of a preferredembodiment of the invention. Referring particularly to the drawings:

Figure 1 is a sectional view, partially in elevation, of a single pole,liquid immersed circuit interrupter which utilizes multi-break contactstructures according to the present invention;

Fig. 2 is an enlarged sectional view, partially in elevation, of one ofthe stationary contact assemblages forming a part of the interruptershown in Fig. 1;

Fig. 3 is an enlarged sectional view of a portion of the stationarycontact assemblage shown particularly in Fig. 2, the. single pair ofcooperating contacts shown are in the open circuit position and theassociated arc extinguishing device is in section;

Fig. 4 is an enlarged sectional view line IV-IV of Fig. 2;

Fig. 5 is an enlarged sectional view taken on the line VV of Fig. 2; and

Fig. 6 is a plan view of one of the contact members used in the contactassemblages shown particularly in Fig. 2.

The circuit. breaker shown in Fig. 1 includes a cylindrical tank I, ofsheet steel or other suitable material, a flanged cover 3 fastenedthereto by bolts 5 or other means, a pair of insulating bushings l,which are rigidly supported upon the cover 3 and extend through theopenings 9 formed therein into the inner portion of the tank i, astationary contact assemblage il mounted upon the lower end of each ofthe insulated bushings l, a bridging contact l3 which is movable intoand out of engagement with the stationary contact assemblages ii toeffect the operation of the breaker, and actuating mechanism (not shown)for moving the bridging contact l3 from one position to the other. A rodI5 or other means of conducting material extends through each of theinsulating bushings l in order to allow the breaker to be connected intoan electrical circuit. A body of insulating liquid ll, preferably 011,is contained within the taken on the tank land the level of this liquidis normally 5 kept sufficiently high to assure that the stationarycontact assemblages H and the movable bridging contact l3 shall besubmerged therein at all times.

As is shown particularly in Figs. 2 and 4, the various structuralelements of eachof the stationary contact assemblages II are mountedbetween a pair of opposed support plates IQ of insulating material. Astationary support member 2| of conducting material, is bolted to theupper end of each of the pairs of opposed side plates I9 and constitutesthe means for supporting each of the assemblages upon the lower end ofthe conductor |5 forming a part of the associated bushing 1.

Four pairs of separable contacts are provided for each of the stationarycontact assemblages H, and each of these pairs includes one of thepivotally supported contact members 23, shown particularly in Figs. 3and 4. The contact members 23 are substantially X-shaped (plan view) andare each supported upon a pivot pin 25 which extends through both of theopposed side members 9 supporting the assemblage. They are each biasedtoward the cooperating contact therefor by two biasing springs 21, whichsprings are held in position by suitable recesses 29 formed in thecontact members. Movement of each of the contact members 23 in thedownward direction under the biasing action of these springs 21 islimited by the proximity of the adjacent arc extinguishing device 3|,one of which devices is associated with each of the pairs of contacts.

The other contact member 33 for each of the pairs of separable contactsis shown particularly in Fig. 6, and comprises a T-shaped member (planview) having an upturned end 35 for engaging the contact portion 31 ofthe cooperating contact 23. The contacts 33 are pivotally supported uponpins 39 which extend through the two opposed support plates l9, and theyare mechanically interconnected by a tie rod 4| of insulating materialwhich extends through the central opening 43 formed therein, this tierod being pivotally connected to each of the contact members 33 by asuitable pivot pin 45. The interconnected contact members 33 are biasedtoward the open circuit position by a pair of springs 41, one end ofeach of which is connected to the pivot pin 46 connecting the lowermostcontact 33 with the common actuating member 4|, and the other end ofeach of which is connected to a pin 49 extending through the two opposedside members l9.

As mentioned above, an arc extinguishing device 3| is associated witheach of the pairs of separable contacts which form a part of thestationary contact assemblages I I. Each of these are extinguishingdevices 3| comprises a stack of plates of insulating material, each ofwhich plates has a slotted opening 5| formed therein. The plates areassembled upon four through bolts 53 of insulating material and slottediron plates 55 are interposed in the stack structure at spacedintervals. The slots 5| in the several plates align to form an arcpassage 51 having a length several times its maximum width, and it iswithin this passage 57 that the arc incident to the separation of eachof the pairs of cooperating contacts is established. The proximity ofthe slotted iron plates 55 to the are so alters the magnetic field setup thereby that the arc is moved longitudinally within the passageformed by the aligned slots.

A quantity of the arc extinguishing liquid l1 is entrapped within eachof the passages 51 where-' in the individual arcs are drawn and aremoved, and this liquid is at least partially volatilized during the arcextinguishing operation by being brought in contact therewith. Theresulting outflowing fluid, part of which is in the vapor and part ofwhich is in the liquid state, causes a transverse blast through the arcand out vents 60 to effect a rapid extinguishment of the arc. Certain ofthe plates comprising the stack structures are provided with cut-outportions 58 for defining liquid retaining pockets which assure anadequate supply of arc extinguishing gas at all times during theoperation of the extinguisher. For a more complete description of anarc-extinguishing device of this type, reference may be had to PatentNo. 2,039,054, issued April 28, 1936, to S. H. Boden and S. T.Schofield, and which is assigned to the assignee of this invention.

The upper plate 59 in each of the arc extinguishing structures 3| issubstantially square and is provided with four suitably threadedopenings 6| formed therein for permitting the plate to be bolted to theside members I!) which support the several elements of the contactassemblage. Through this arrangement, each of the are extinguishingdevices 3| is individually supported in position in the completedstructure by means which allows that device to be readily removed forinspection or other purposes. The devices 3| are so arranged, of course,that the contact portion 35 of the T-shaped contact member 33 moveswithin the passage 51 formed therein when it is being moved into and outof engagement with its cooperating contact member 23.

The several pairs of contacts are electrically connected in series witheach other by a plurality of flexible shunts 63, one end of each ofthese shunts being bolted to each of the adjacent contacts 23 and 33.The upper contact member 23 is electrically connected to the supportmember 2| which engages the conductor |5 disposed within the associatedinsulating bushing I by means of a pair of similar shunts 65.

The bridging contact I3 includes an actuating rod 61 of insulatingmaterial which is engaged by the breaker actuating mechanism, a bridgingportion 69 of conducting material and a pair of upstanding contactportions ll, one of which is adapted to engage and eifect the actuationof each of the stationary contact assemblages A suitable contact 13 forcooperating with each of these upstanding contact portions "II issupported upon the lower end of each of the tie members 4|, whichinterconnects the T-shaped contacts 33 in the stationary contactassemblages Entry of the cooperating upstanding contact portion 1| intothe contact 13 is facilitated by a V-shaped guide 15 forming a partthereof, and the opposed contact members 11 which directly engage thesides of the upstanding contact portion 1| which is moved therebetweenare biased toward each other by suitable leaf springs 19. The lower endof each of the lowermost shunts 63 in each of the contact assemblages isbolted to the contact means 13 in order to complete the electricalcircuit through the interrupter.

Since the interconnected T-shaped contacts 33 are biased toward the opencircuit position, proper engagement of the upstanding contact portionsII with the contact means 13 is assured during each operation of theinterrupter. The device is so arranged that the upstanding contactportions disengage the contact means 13 during the final sta es of eachcircuit opening operation.

Thus, two gaps of insulating fluidin addition to the gap existing withinthe contact assemblages l I are interposed in the electrical circuitthrough the interrupter when that device is in the open circuitposition. This providesan increased factor of safety during theoperation of the interrupter.

The interrupter is shown in the closed circuit position in Fig. 1. Uponthe operation of the actuating mechanism, either in response to anoverload in the controlled circuit or other means, the movable bridgingcontact l3 begins to move downwardly away from the two stationarycontact assemblages Ii. The springs 41, which bias the interconnectedT-shaped contacts 33 away from the cooperating contacts 23 therefor,cause the interconnected contacts 33 in each of the assemblages l l tomove downwardly with the downwardly moving bridging member. As a result,a plurality of serially connected arcs are established within each ofthe stationary contact assemblages ll, each individual arc beingestablished within the passage 51 formed within one of the areexcontacts 33, to the center of the pivot pin 39 which supports-thatcontact 33 is considerably less (about one-half) than the distance fromthe center of the support pivot pin 39 to the point of engagement of theT-shaped contact. 33 with its cooperating contact 23, the speed ofseparation of each of the pairs of cooperating contacts is at leastdouble the speed of movement of the bridging contact l3. Thus, thecircuit through the interrupter is opened at a rate which is at leastsixteen times the speed of movement of the bridging contact l3, andfurther, since each of the serially connected arcs is drawn within anindividual arc extinguishing device, the efliciency of arc extinction isbrought to an extremely high value.

The very high speed at which the electrical circuit through theinterrupter is opened makes possible the utilization of breakersemploying this form of contact structure in very high voltage circuits,and by proper design of the parts extremely large amounts of power maybe interrupted thereby.

As the circuit opening operation progresses, the downwardly movinginterconnected contacts 33 reach their limit of motion and subsequentmove ment of the movable bridging contact l3 causes the upstandingcontact portions Ii thereof to disengage the conducting means 13aiilxedto the lower end of each of the common actuating members 4 l. Theamount ofposslble downward movement of the movable bridging contact [3is so arranged that a substantial gap of predetermined length existsbetween the upstanding contact portions H and the cooperating conductingmeans 13 therefor when the breaker is in the open circuit position. Thisassures that an insulating gap shall exist between the bridging contactl3 and each of the cooperating stationary contact assemblages i I whenthe interrupter is in the open circuit position.

This gap, in series with the arc-rupturing contacts, may be made of any.desired length when the movable contact member is in the open positionwithout affecting the break distance or length of separation of theintermediate arcdrawing contacts. It will be apparent, therefore, thatthis final insulating gap alone can be relied upon for protectionagainst voltage surges or high potentials from any source which may beimpressed upon the circuit breaker when it is standing in its openposition. The distance to which the intermediate, arc drawing contactsare separated will, then, be governed only by the length 01' are mostsuitable for interrupting purposes at that voltage for which the circuitbreaker is designed, and will be in no way affected by considerations ofinsulation safety while the contacts stand in their open position. Ihave, therefore, by my invention separated the main functions of an opengap between contacts-arc in terruption and insulation safetyinto its twosubdivisions and have provided separate insulating gaps, eachparticularly designed to carry out its own function most effectively foraccomplishing each function. In theprevious devices of like nature bothfunctions have been performed by a single gap, or series of gaps, andthe result has been a compromise in design which did not permit the mosteffective performance of either function.

While in accordance with the patent statutes, I have, in the foregoing,disclosed the details of one embodiment of my invention, it is to beunderstood that these details are merely illustrative and thatvariations in the structure shown will be both necessary and desirablein certain instances. It is my wish, therefore, that the lansaidintermediate means including a plurality of pairs of serially connected,cooperating contacts and means for causing said pairs of contacts toseparate simultaneously when said movable contact is moved to theopen-circuit position in order V to efiect the establishing of aplurality of serially connected arcs, said last mentioned means causingthe separation of each pair of said cooperating contacts to take placeat a speed of movement which is greater than the speed of movement ofsaid movable contact.

2. In a circuit interrupter, a stationary support means which is atleast partially of conducting material and which is electricallyconnected to one of the terminals of said interrupter, a stationarycontact assemblage supported thereby, a movable contact for cooperatingwith said sta- "tionary contact assemblage, and actuating means formoving said movable contact to an open and to a closedcircuit position,said stationary contact assemblage including a plurality of pairs of.

3. In a circuit interrupter, a contact structure including a pluralityof pairs of cooperating contacts, at least one of each of said pairs ofcontacts comprising a pivotally supported member movable into and out ofengagement with the cooperating contact therefor, means for electricallyconnecting said pairs of contacts in series, actuating means for saidcontacts including a contact actuating member having releasableengagement with at least one of said contacts, and means whereby themovement of said contact actuating member causes the simultaneousseparation of each of said pairs of cooperating contacts, at a speedgreater than the speed of movement of said actuating member, said lastmentioned means including a motion-magnifying means interconmeeting allof said pivotally supported contact members.

4. In a circuit interrupter, a stationary conducting means, a movablecontact, actuating means for moving said movable contact to an open andto a closed circuit position, and means positioned intermediate saidstationary conducting means and said movable contact when saidinterrupter is in the closed circuit position for completing the"electrical circuit therebetween, said intermediate means including aplurality of pairs of cooperating contacts, at least one of the contactsof each of said pairs comprising a pivotally supported member movableinto and out of engagement with its cooperating contact, means forelectrically connecting said pairs of contacts in series with eachother, arc extinguishing means associated with each of said pairs ofcontacts, and means actuated by said actuating means whereby each ofsaid pivotally supported contact members may be moved simultaneouslyfrom the closed circuit position to the open circuit position in orderto effect the establishing of a plurality of serially connected arcs,said last mentioned means causing the separation of each pair of saidcooperating contacts to take place at a speed of movement which isgreater than the speed of movement of said movable contact.

5. In a contact structure for a circuit interrupter, a plurality ofpairs of separable contacts, at least one of each oi said pairs ofseparable contacts comprising a pivotally supported member movable intoand out of engagement with the other member of said pair, and means forsimultaneously actuating said contact members comprising a bar whichengages each of said pivotally supported contact members during theoperation of said contact structure, the shortest distance between thepivot point of each of said pivotally supported contact members and thepoint at which that member is engaged by said actuating bar being lessthan the shortest distance from the pivot point of each of saidpivotally supported contact members to. the point at which that memberengages the cooperating contact member therefor, this arrangementcausing the separation of each of said pairs of contacts to take placeat a greater speed than the speed of movement of said common actuatingbar therefor.

6. In a contact structure for a circuit interrupter, a plurality ofresiliently supported contact members, a plurality of pivotallysupported contact members, one of which is adapted to cooperate witheach of said resiliently supported contact members, means forelectrically connecting said pairs of cooperating contacts in serieswith each other, and a common actuating means for simultaneously movingall of said pivotally supported contacts into and out of engagement withthe cooperating contact therefor, said common actuating means comprisinga member pivotally connected to each of said pivotally supported contactmembers, the shortest distance between the point at which said member ispivotally connected to each of said contact members and the pivot pointof that member being sub' stantially less than the shortest distancebetween the pivot point of said contact member and the point at whichthat member engages the cooperating contact therefor in order that theseparation of said contact members may be effected at a greater speedthan the speed of motion of said common actuating member.

'7. In a circuit breaker, a plurality of pairs oi separable contacts,means for connecting said contacts in series, and common actuating meansfor simultaneously separating all of said pairs of contacts except one apredetermined distance to form a plurality of serially related arcs oflimited are energy and for subsequently separating the remaining pair ofcontacts a greater distance to provide an insulating gap capable ofwithstanding high voltage.

8. In a circuit breaker, a plurality of are extinguishing units, a pairof separable contacts within each unit, means connecting said pairs ofcontacts in series, common actuating means for simultaneously separatingsaid pairs of contacts a predetermined distance to establish a pluralityof serially related arcs, an additional pair of separable contactsconnected in series with said plurality of pairs of contacts anddisposed exteriorly of said arc-extinguishing units, said additionalpair of contacts being adapted to be separated a distance greater thanthe separation of said simultaneously actuated pairs of contacts by saidactuating means subsequent to the opening of said simultaneouslyactuated pairs of contacts.

9. In a. circuit breaker, a plurality of arc extinguishing unitsarranged end to end, a relatively fixed and a movable contact for eachunit, means for connecting said contacts in series, means including acommon actuating member operatively coupling said movable contacts intandem for simultaneous operation to open and closed positions, acontact carried by said actuating member and connected in series withthe contacts of said units, and a second actuating member having acontact thereon adapted for releasable contacting engagement with thecontact on said first actuating member, said second actuating memberbeing movable with said first actuating member during the opening ofsaid movable contacts for maintaining the contacts carried by saidrespective members in engagement and movable therefrom immediatelyfollowing the opening operation of said movable contacts to cause aseparation of said contacts carried by said respective actuatingmembers,

10. In a circuit breaker, a plurality of are extinguishing units, arelatively fixed and a movable contact for each unit, means forconnecting said contacts in series, means including an operating rodcoupling said movable contacts in tandem for simultaneous operation toopen and closed positions, means biasing said movable contacts to theopen position, a contact member secured to one end of said actuating rodand connected in series with the contacts of said units, an actuatingmember having a contact member thereon for cooperative engagement withthe contact member on said rod, said actuating member being movable inone direction for engaging said contact member and for causing saidoperating rod to move said movable contacts to the closed positionagainst said'biasing r pe-ls, said actuating member being movableili'the oppositedirection to open said contact members, said lattermovement enabling said biasing means to move said movable contacts tothe openv position prior to the final separation. of said contactmembers.

11. Ina circuit interrupter, an enclosure having an insulating liquidtherein, a plurality of arc-extinguishing units, means for supportingsaid units in aligned spaced relation within said enclosure, each ofsaid units-having an arc chamber therein, a contact member yieldinglysupported on each unit having a contact portion extending within the arcchamber of the unit, a movable contact member for each unit having acontact portion thereon for cooperative engagement with said first-namedcontact portion, means for connecting the cooperating pairs oi contactsof said units in series, means for pivotally supporting said movablecontact members, a common operating rod coupled to each of said movablecontact members and operable to simultaneously rock said movable contactmembers about their pivotal supports to open and closed positions, meansbiasing said movable contact arms to the open position, an auxiliarypair of contacts One of which is secured to one end of said operatingrod and connected in series with the contacts of said units, and anactuating member supporting the other of said auxiliary pairs ofcontacts, said actuating member being movable in one direction to causethe engagement or said auxiliary pair of contacts and the movement ofsaid operating rod to the closed position, and movable in the oppositedirection to cause said biasing means to operate said contact arms tothe open position prior to the opening of said auxiliary pair ofcontacts.

12. In a circuit interrupter, a tank, an insulating liquid within saidtank, an arc-extinguishing assemblage supported within said tankcomprising a plurality of arc-extinguishing units arranged end to end inaligned spaced relation, a pair of cooperating contacts within eachunit, a movable carrier for at least one of the contacts of each pair ofcontacts, a common actuating member operatively coupled to said contactcarriers for simultaneously separating said pairs 01' contacts apredetermined distance to establish a series are within each of saidarc-extinguishing units, an auxiliary pair of separable contactsconnected in series with said simultaneously actuated contacts, andmeans for operating said actuating member, said last-named means beingoperable to separate said auxiliary pair or contacts subsequent to theseparation of said simultaneously actuated contacts, and to provide areater gap distance between said auxiliary contacts than between saidsimultaneously actuated contacts.

13. In a circuit breaker, a plurality of pairs or separable contacts,means for connecting said contacts in series and a common actuatingmeans for simultaneously separating all of said pairs of contacts exceptone a predetermined distance to form a plurality of serially relatedarcs of limited are energy and for subsequently separating the remainingpair of contacts a greater distance to'provide'an insulating gap capableof withstandinghigh voltage, said common actuating means including meansfor biasing said simultaneously separable pairs of contacts to the opencircuit position independently of the force applied by said actuatingmeans for separating said remaining pair of contacts.

14. In a circuit breaker, an arc extinguishing structure, a plurality oipairs of separable contacts for drawing a plurality oi arcs within saidarc-extinguishing structure, means connecting said pairs of contacts inseries, a common actuating means for simultaneously separating saidpairs of contacts a predetermined distance to establish a plurality ofserially related arcs, means biasing said simultaneously actuated pairsof contacts to the open circuit position, an additional pair ofseparable contacts connected in series with said plurality of pairs ofcontacts and disposed exteriorly of said are extinguishing structure,said additional pair of contacts being adapted to be separated adistance greater than the separation of said simultaneously actuatedpairs of contacts by said actuating means subse quent to the opening ofsaid simultaneously actuated pairs of contacts, said biasing means beingoperative to move said simultaneously actuated pairs of contacts to theopen circuit position independently of the force applied by saidactuating means for separating said additional pair 01' contacts.

15. In a circuit breaker, a plurality'of pairs of separable contacts,means for connecting said contacts in series, and common actuating meansfor simultaneously separating a, plurality of said pairs of contacts apredetermined distance to form a plurality of serially related arcs oflimited are energy and for subsequently separating at least one of saidpairs of contacts a greater distance to provide an insulating gapcapable of withstanding high voltage.

16. An electric circuit interrupter of the extinguishing chamber typecomprising insulating casing means forming pressure-confining chambermeans, an arc-extinguishing liquid substantially filling said chambermeans, a plurality oi. contact members, each pivotally mounted withrespect to said casing means and disposed to move within said chambermeans, coacting fixed contact structure arranged to form with saidcontact members a plurality oi breaks in series in the circuit, saidcasing means having a pressure exhaust port opposite each 01' saidbreaks, an operating member for moving said contact memberssubstantially in unison, a disconnecting contact connected in serieswith said contact members and carried by said operating member at oneend of said chamber means, and a movable switch member for coacting withsaid disconnecting contact exteriorly of said chamber means.

17. An electric circuit breaker of the liquid blast type comprisingpressure confining casing means, an arc-extinguishing liquid in whichsaid casing means is immersed, relatively movable contacts mounted tomove within said casing means arranged to form at least two breaks inseries in the circuit to be interrupted, said casing means having anexhaust port disposed adjacent and opposite one of said breaks andarranged so that arc pressure created within said casing means iseffective to drive arc-extinguishing liquid through said port toextinguish the arc thereat, and a movable switch member operable withinsaid liquid exteriorly of said casing means for controlling the movablecontact structure in said casing means and being in series therewith,circuit opening movement of said switch member causing initiallyseparation of the contact structure within said casing means forinterrupting the circuit and subsequently separation of said switchmember from said contact structure to form an isolating gap in saidliquid.

18. An electric circuit breaker of the fluid blast type comprisingrelatively movable contact structure separable to open the circuit,pressure confining chamber means for enclosing a comparatively fixedportion of said contact structure, said fixed portion including aplurality of contact elements adapted to form a plurality of breaks inseries in the circuit, said chamber means being provided with exhaustports disposed opposite certain of said breaks so that pressure withinsaid chamber means is eflective to drive arc-extinguishing fluid throughthe breaks at said ports, means for moving said contact elements towardsopen-circuit position, and movable switch structure coacting with saidcontact elements exteriorly of said pressure-confining chamber means soas to move said contact elements to the closed circuit position and tobreak connection therewith subsequent to circult-opening movement ofsaid contact elements.

19. An electric circuit breaker of the fluid blast type comprisingrelatively fixed contact structure adapted to form a plurality of breaksin series, means forming pressure-confining chamber means for saidcontact structure, a movable switch member adapted to beconnected inseries with said fixed contact structure opable exteriorly of saidchamber means, a source of arc-extinguishing fluid, said chamber meanshaving exhaust ports opposite certain of. said breaks so that pressurewithin said chamber means is eflective to drive arc-extinguishing fluidthrough the breaks at said ports, said movable switch member beingoperative to move said flxed contact structure to close said breaks inthe circuit-closing operation and adapted in the circuit-openingoperation to form an isolating break with respect to said fixedstructure subsequent to formation of the aforesaid breaks in saidchamber means.

20. An electric circuit breaker of the fluid blast type comprising fixedinsulating casing means forming extinguishing chamber means, relativelymovable contacts mounted for limited movement within said chamber meansand arranged to form a plurality of breaks in series in the circuit, asource of arc-extinguishing fluid, said insulating casing means havingexhaust ports opposite certain of said breaks so that pressure withinsaid chamber means is efiective to drive arc-extinguishing fluid throughthe arcs at said breaks, means for operating as a unit said contactstructure within said extinguishing chamber means and a coacting movableswitch member operable exteriorly of said chamber means for biasing saidunit to the closed circuit position in accordance with thecircuit-closing operation and for controlling opening movement of saidunit in accordance with initial circuit-opening movement of said switchmember, the circuitopening operation within said chamber means beingeffective to interrupt said circuit independently of said movable switchmember, and said movable switch member being movable to form anisolating gap between said member and said extinguishing chamber means.

' 21. In a circuit interrupter, an outer casing, an arc-extinguishingstructure in said outer casing, a plurality of pairs of separablecontacts electrically connected in series for drawing a plurality ofrelatively short arcs within said arcextinguishing structure, a pair ofdisconnecting contacts electrically connected in series with saidplurality 01' pairs of contacts, one of said disconnecting contactsbeing movable within said outer casing to a point a considerabledistance away from said arc-extinguishing structure, and operating meansfor first separating said plurality of pairs oi. contacts and thenseparating said pair of disconnecting contacts.

22. In a circuit interrupter, a casing, a body of arc-extinguishingliquid therein, an arc-extinguishing structure in said body of liquid, aplurality of pairs of separable contacts electrically connected inseries for drawing a plurality of relatively short arcs within saidarc-extinguishing structure, a pair of disconnecting contactselectrically connected in series with said plurality of pairs ofcontacts, one of said disconnecting contacts being movable through saidarc-extinguishing liquid to a point a relatively great distance awayfrom said arc-extinguishing structure, and operating means for firstcausing said plurality of pairs of contacts to begin to separatesubstantially simultaneously to interrupt the current in saidarc-extinguishing structure and for then separating said pair ofdisconnecting contacts.

23. In a circuit interrupter, an arc-extinguishing structure, aplurality of pairs of separable contacts electrically connected inseries for drawing a plurality of relatively short arcs within saidarc-extinguishing structure, actuating means connecting said pluralityof pairs of contacts, means biasing said actuating means and saidplurality of pairs of contacts to move to separated position, a pair ofdisconnecting contacts electrically connected in series with saidplurality of pairs of contacts, one oi. said disconnecting contactsbeing mechanically connect ed to said actuating means and the other ofsaid disconnecting contacts being movable in one direction to engage thefirst said disconnecting contact and thereafter move said actuatingmeans and said plurality of pairs of contacts to engaged positionagainst their bias and bein movable in the other direction to cause saidplurality of contacts to begin to separate substantially simultaneouslyand to thereafter separate from the first said disconnecting contact andmove to a point at a considerable distance from said arc-extinguishingstructure.

24. In a circuit interrupter, a casing, a body 01 arc-extinguishingliquid therein, an arc-extinguishing structure in said body of liquid, aplurality of pairs of separable contacts electrically connected inseries for drawing a plurality of relatively short arcs within saidarc-extinguishing structure, said arc-extinguishing structure includingpressure-confining chamber means for causing fluid to flow through atleast several of said arcs to quickly extinguish them and interrupt thecircuit, actuating means connecting said plurality of pairs ofcontacts,means biasing said actuating means and said plurality of pairs ofcontacts to move to separated position, a pair of disconnecting contactselectrically connected in series with said plurality of pairs ofcontacts one of said disconnecting contacts being mechanically connectedto said actuating means and the other of said disconnecting contactsbeing movable in one direction to engage the flrst said disconnectingcontact and thereafter move said actuating means and said plurality ofpairs 01' contacts to engaged position against their bias and beingmovable in the other direction to cause said plurality of contacts tobegin to separate substantially simultaneously and to separate from thefirst said disconnecting contact after the current has been interruptedin the arc-extinguishing structure and to move to a point within saidcasing at a relatively great distance from said arc-extinguishingstructure.

25. An electric circuit breaker of the liquid blast type comprisingrelatively movable contact structure separable within anarc-extinguishing liquid, insulating pressure confining chamber meansfor enclosing a comparatively fixed portion of said contact structure,said fixed portion including aplurality of contact elements adapted toform a plurality of breaks in series in the circuit, said chamber meansbeing provided with exhaust ports disposed adjacent and opposite certainof said breaks so that are pressure created within said chamber means iseffective to drive arc-extinguishing liquid through the breaks at saidports, means for biasing said contact elements towards open-circuitposition, and movable switch structure coacting with said contactelements exteriorly of said pressure-confining chamber means so as tobias said contact elements to the closed circuit position and to breakconnection therewith subsequent to circuit-opening movement of saidcontact elements.

26. An electric circuit breaker of the liquid blast type comprisingrelatively fixed contact structure adapted to form a plurality of breaksin series, insulating casing means forming pressure-confining chambermeans for said contact structure, a movable switch member adapted to beconnected in series with said fixed contact structure operableexteriorly of said chamber means, an arc-extinguishing liquid in whichsaid fixed and movable contact structures are immersed, said insulatingcasing means having exhaust ports adjacent and opposite certain of saidbreaks so that arc pressure created'within said chamber means isefiective to drive arc-extinguishing liquid through the breaks at saidports, said movable switch member being operative to ,bias said fixedcontact structure to close said breaks in the circuit-closing operationand adapted in the circuit-opening operation to form an isolating breakwith respect to said fixed structure subsequent to formation of theaforesaid breaks in said chamber means.

27. An electric circuit breaker of the liquid blast type comprisingfixed insulating casing means forming an extinguishing chamber means.relatively movable contacts mounted for limited movement within saidchamber means and arranged to form a plurality of breaks in series inthe circuit, an arc-extinguishing liquid in which said insulating casingmeans is immersed, said insulating casing means having exhaust portsadjacent and opposite certain of said breaks so that are pressurecreated within said chamber means is efi'ective to drivearc-extinguishing liquid through the arcs at said breaks, means foroperating as a unit said contact structure within said extinguishingchamber means and a coacting movable switch member operable in saidarcextinguishing liquid exteriorly of said chamber means for biasingsaid unit to the closed circuit position in accordance with thecircuit-closing operation and for controlling opening movement of saidunit in accordance .with initial circuitopening movement of said switchmember, the circuit-opening operation within said chamber means beingeffective to interrupt said circuit independently of said movable switchmember, said movable switch memberbeing movable into saidarc-extinguishing liquid so as to form an isolating gap between saidmember and said extinguishing chamber means.

28. An electric circuit breaker of the fluid blast type comprisingpressure confining casing means, an arc-extinguishing liquid in whichsaidcasing means is immersed, relatively movable contacts mounted tomove within said casing means arranged to form at least two breaks inseries in the circuit to be interrupted, said casing means having anexhaust port disposed opposite one of said breaks and arranged so thatare pressure created within said casing means is effective to drivearc-extinguishing fiuid through said port to extinguish the arc thereat,and a movable switch member operable within said liquid exteriorly ofsaid casing means for controlling the movable contact structure in saidcasing means and being in series therewith, circuit opening movement ofsaid switch memb'er causing initially separation of the contactstructure within said casing means for interrupting the circuit andsubsequently separation of said switch member from said contactstructure to form an isolating gap in said liquid.

29. An electric circuit breaker of the fluid blast type comprisingrelatively movable contact structure separable within anarcextinguishing liquid,

insulating pressure confining chamber means for enclosing acomparatively fixed portion of said contact structure, said fixedportion including a plurality of contact elements adapted to form aplurality of breaks in series in the circuit, said chamber means beingprovided with exhaust ports disposed opposite certain of said breaks sothat are pressure created within said chamber means is effective todrive arc-extinguishing fluid through the breaks at said ports, meansfor bias ing said contact elements towards open-circuit position, andmovable switch structure coacting with said contact elements exteriorlyof said pressure-confining chamber means so as to bias said contactelements to the closed circuit position and to break connectiontherewith subsequent to circuit-opening movement of said contactelements.

30. An electric circuit breaker of the fluid blast type comprisingrelatively fixed contact structure adapted to form a plurality of breaksin series, insulating casing means forming pressureconfining chambermeans for said contact structure, a movable switch member adapted to beconnected in series with said fixed contact structure operableexteriorly of said chamber means, an arc-extinguishing liquid in whichsaid fixed and movable contact structures are immersed, said insulatingcasing means having exhaust ports opposite certain of said breaks sothat are pressure created within said chamber means is ber means.

31. An electric circuit breaker of the fiuid blast type comprising fixedinsulating casing means forming an extinguishing chamber means,relatively movable contacts mounted for limited movement within saidchamber means and arranged to form a plurality of breaks in series inthe circuit, an arc-extinguishing liquid in which said insulating casingmeans is immersed, said insulating casing means having exhaust portsopposite certain of said breaks so that are pressure created within saidchamber means is effective to drive arc-extinguishing fiuid through thearcs at said breaks, means for operating as a unit said contactstructure within said extinguishing chamber means and a coacting movableswitch member operable in said arc-extinguishing liquid exteriorly ofsaid chamber means for biasing said unit to the closed circuit positionin accordance with the circuit-closing operation and for controllingopening movement of said unit in accordance with initial circuit-openingmovement of said switch member, the circuit-opening operation withinsaid chamber means being effective to interrupt said circuitindependently of said movable switch member, said movable switch memberbeing movable into said arc-extinguishing liquid so as to form anisolating gap between said member and said extinguishing chamber means.

32. In a circuit breaker, a plurality of movably mounted contactselectrically connected in series, arc-extinguishing means for the areestablished at each of a plurality of said contacts, means forsimultaneously moving a plurality of said contacts to draw a pluralityof arcs to a length which is sufficient to cause efiicient extinguishingof said arcs by said arc-extinguishing means but which is insufllcientto provide a gap which can be relied upon to meet the normal opencircuit insulation requirements of the circuit breaker, and one of saidcontacts being automatically movable after the extinguishing of saidarcs upon each opening operation of the circuit breaker to provide a gapwhich is suflicient to meet the normal open circuit insulationrequirements of the circuit breaker.

33. In a circuit breaker, a plurality of movably mounted contactselectrically connected in series, arc-extinguishing means in which aplurality of said contacts establish a plurality of arcs, means forsimultaneously moving said plurality of contacts for establishing theplurality of arcs in the arc-estinguishing means to draw said pluralityof arcs to a length which is sufficient to cause efiicient extinguishingof said plurality of arcs by said arc-extinguishing means but which isinsufficient to provide a gap which can be relied upon to meet thenormal open circuit insulation requirements of the circuit breaker, andone of said movably mounted contacts being automatically movable outsideof said arc-extinguishing means after the extinguishing of said arcsupon each opening operation of the circuit breaker to provide a gapwhich is sufiicient to meet the normal open circuit insulationrequirements of the circuit breaker.

JOHN B. MACNEILL.

